Classic Sci-fi Horror like H.P. Lovecraft?

(Reposting from r/WhatsThatBook)

Classic Sci-fi Horror like H.P.Lovecraft?

Theres this video essay is watched probably two years ago now that I can't find. It talked about a novel that was like (or could have been) H.P. Lovecraft's eldritch stuff. It had the title along the lines of 'The scariest novels that no one has read' or 'that I've read'. Again, cant remember. Cannot find this video anywhere either. But in the video it spoke of a few novels. One I really connected with was probably the middle one, where the guy spoke of this frankenstein-esque plot of a mad scientist putting his friends brain into a Nessie type sea creature. First the friend is fine, human-like, but after a while the animalistic instincts take over. The novel seemed to be exploring human and animal life and behavior as well as ethics around creating such life and abominations. The horror aspect came from watching the friends humanity deteriorate.

Im super into this stuff. Frankenstein and Eldritch horror is a favorite of mine and ethical debates like this are awesome. Please, If anyone knows of this one. No websites that promise to find novel titles by plot can find it and the video is gone. It honestly pains me.